Pulverization of coal



March 9 1,926.

H. KREISINGER PULVERIZATION OF COAL 2 Sheet's-Sheet 1 Filed Jan. 16, 1925 INVENTR A TTORNEYS March 9 1926.

H. KREISINGER PULVERIZATION 0F COAL Filed Jan. 1G, 1925 2 SheetsSheet 2 Y INVENTOR ATTORNEYS Patented Maffe, 1926.

. UNITED STATES PA'rE-NT'oF HENRY KAREISINGER, OF PIERMONT, NEW YORK, ASSIGNOR TO .COMBUSTION ENGI- 'NEFRIQ'G CORPORATION, 0F NEW YORK, N. Y., A CORPORATION OF NEW YORK..

n P'ULVERIZATION OF COAL.

, tion is to simplify and'materially reducethe 'cost of preparation and pulverization of the coal. In this connection avery large item. of expense ls'the drying of the coal which y. has inherent moisture and also, very frequently, considerable surface moisture. Usually the `content of inherent moisture is such as to introduce diiiiculties not only with respect to the preparation and handling of the coal, but also its use. The surface moisture adds to the complications. Heretofore, it has been the general practice to dry the coal while in lump form toV drive olf all of the moisture it is desired to remove.v This involves the application of moref heat than I have found to be necessary and involves expense which I have discovered I am enabledl to greatly reduce.

How the foregoing, togetherv with such other objects as may hereinafter appear, or are lncldent tomy invention, are realized, isset forth in the accompanying description of the invention and the apparatus for car- 'rying out the same illustrated in the drawings, wherein- Fig. 1 is a side elevation of one form of apparatusor system suitable for practicing m mvent1on; y

ig. 2 is a diagrammatic side elevation of aiiodification of a detail 'of the invention; an

Figs. 3 and 4 are fragmentary sidey elevaf tions illustrating still other 'modifications of the invention.

v Referring now to the drawings,and par ticularly to 1 thereof, it will be seen'. that from a suitable source of supplyl of raw coal, such as the bunker or bin 7 ,I conduct the coal 'to be crushed to a mill 8- from which al ipe 9 leads to a separator 10, the coal p verized 1n the mill Ibeing conducted to the separatori by a current of air set-up by the fan 11, the coal and air being separated 16, 1925. Serial No. 2,718.

in the separator 10, from which the separated coal is discharged to a bin 12 from which it may be transported -or led to the. burners of a furnace or to a storage bin, not shown.

In the preferred practice of my invention, there is a return pipe 13 from the separator to the mill,- providing a substantially closed circuit.

I apply or supply heat for the system at a suitable point. The amount of heat I sup- FicE. -h

ply is that which, in the pulverization, will evaporate the desired amount of moisture in association with the current of air passing .thru the system, which air absorbs such moisture. Thisproceeds upon the principle that far much less heat is required to dry the coal when it is pulverized, and, or undergoing pulverization, than is required to drive olf suiiicientmoisturc when the coal is in lump form.

According to one form of my invention I pass the coal leaving the-bunker 7 thru a heater'. 14, in which steam or some othersuitable heating medium is applied. In

ass- 'ing thru the heater I do not attempt to drive 0E all ofthe moisthre int-he manner here-4 -tofore practiced, but l propose to heat the ,coal only to the point where the senslble heat remainingdn the coal, upon its introduction into the mill, is such, in association with the current ofl air, as will drive all the necessary amount of moisture. In this connection, it will be seen that when the coal is in a finely divided condition the sensible heat carried by the coal will be such as'to evaporate the moisture to the desired extent. In order to keep down the amount of heat required, I locate the heater lli'comparatively closeto the -mill 8.

v'The air, which liftsthe pulverized coal from the mill 8 thru separator 10, absorbs the moisture and as it is being recirculated continually, the moisture content would rise so high that the air will become saturated, thereby rendering further operation impossible. To overcome this, -I draw oif from Fig.` 1 passes about8,000 cubic feet perl minute 'therethriu and I draw otl'"thru the pipe about 2000 rcubic feet of moisture laden air per minute, admitting napproximately l2000 cubic feetper minute of makeup air thru the pipe 16. In this connectiom the,air which may enter with the coal is more'or lessnegligible for the. reason thatL the bunker usually has a substantial layer of coal in the bottom thereof, acting to some extent as a. seal. In substitution of, or in supplementation of the heater 14, I may admit preheated Aair thru the pipe 16. If this air is sufficiently hot, then preheating of the coal may be dispensed with, or, v' if it is desiredto partially heat the coal leaving the bunker, the balancevof the heat ma be supplied with theair to the pipe 16.

As an alternative hot ,flue gas; may be sup` plied from the stack 18, under control of the valve 19. Thus by the arrangement show-nrin F ig. 1, by closing or opening, or partly closing or opening the valves 20, 17 and 19, all of the-heat required may be supplied to the co as it leaves the bunker; all ofthe heat may besupplied directly toa the mill; or'part of the heat required may be supplied at the heater.14 and part at the mill; or flue gas or hot air, or a'mixture of the two, may be utilized in substitution of the heater 14 in whole or in part. When all of the heat required is supplied with the air or the flue gas and introd ced into the mill, it will be seen that -suoh eat is most' effectively supplied and the amount required will be comparatively very small because of the iiie state of division of the coal.

In the arrangement (shown in Fig. 3, the heat is supplied by means of a steam or other heating coil 21, located around the mill. This is not as desirable as thearrangement previously described.

In the arrangement of Fig. 4, the air supplied for make-up purposes is preheated by passing' over a steam or other heating coil 22. According to this arrangement, additional heat may be applied to advantage on the return side of the system by leading the return pipe 18 thru a steam or other form of heater 23.

I preferin all arrangements, that the return air shall besomewhat less than 200 F.

From the foregoing description my invention, in so far as process is concerned will be understood.

I claim:` v .y 1. The herein described process of pulrerizing coal which consists in pulverizing the coal in the mill of a. system including a separator and air as a carrying medium, and in preheating the coal to be pulverized to a point such that the sensible heat of the coal 1n pulverization is sufficient to dry the coal for transport and in the presence of the carrying air. f

2. The herein described process of pulverizing coal which consists in ipulverizing the coal in the mill of a closed system including a/separator and air as a carrying mediumain preheating the coal to be pulverized to a point such that the sensible heat thereof will dry the coal in pulverization in the presence of the carrying air stream, and in-withdrawing and replacing sufficient of the moisture laden air to allow the process to continue.` v

3. The herein described process of pulverizing coal which consists in pulverizing thecoal in the mill of a closed system including4 a separator and air as a carrying medium; in preheating the Acoal to be pulverized to a point such that the sensible heat thereof will dry the coal in pulverization in the presence of the carrying air stream, and in withdrawing Aand .replacing suiiicient of the moisture laden air to allow the process to continue, the makeup being vin the form of a heated gaseous medium. v 4. The-herein described process of pulverizing coal which consists in pulverizing the coal in, the mill of a closed system including a separator and air as a carrying medium in preheating the coal to be pulverized to a point suchthat the sensible heat\ thereof will dry the coal in pulverization in the presence yof the carrying air stream, and in withdrawing andreplacing sufficient of the moisture laden air to allow the process to continue, the makeup being in the form of a heated gaseous medium, all with the maintenance of temperature conditions such that detrimental condensation in the separated coal is avoided.

5. In a fuel pulverizing system, a mill,.a separator, suitable piping between mill and separator and separator and mill, means for setting up an air current within the system, a source of y.supply of fuel to be pulverized, means for introducing heat into the system, and means for withdrawing moisture laden gas from the system.

6. In a fuel pulverizing system, a mill, a separator, suitable' piping between mill and separator and separator and mill, means for setting up an air current within the system, a source of supply of fuel tobe pulverized, ymeans for introducing heat into the system with the coal, and means for withdrawing moisture laden gas from thc system.

7. In a fuel pulverizing system, a mill, a.- separator, suitable piping between mill and separator and separator and mill, means for setting up an air current within the system` a `source of supply offuel to be pulverized, means for introducing heat into the system through the mill, and vmeans for withdrawing moisture laden gas from the system.

8. In a fuel pulverizing system, a mill, a separator, suitable piping between mill and separator and separator and mill, means for setting up an air current within the system, 13

a source of supply of fuel to be pulverized, means for withdrawing moisture laden gas from the system and means for nsupplying makemp for the system, said make-up carrying heat.

9'.v In a fuel pulverizing system, a mill, a separator, suitable piping between mill and t separator and separatorJand mill, means for setting up an air current within the system, 10 a source of supply of fuel to be pulverized, means for introducing hot flue gas into the system, and means for withdrawing moisture laden gas from the system.

10. In a Afuelpulverizing system, a mill, a l5 separator, suitable pipingbetw'een mill and "separator and separator and mill, means for setting up an air current within the system, al source of supply of fuel to be pulverized, means for\ introducing heat into the system '20 Y from the burning of the product of the system, and means for withdrawing moisture laden gas from the system. l p l1. In combi ation `in a fuel preparing system, a sour of coal supply,J a mill, a

separator, piping from the mill to the separator, means setting `up a carrying current ofgas through the system, and means for introducingheat into the system whereby in pulverization sufficient moisture is evaporatecl and taken up by the gas.

-l2. In combination in ay fuel preparing system, a source'of coal supply, a mill, a separator, piping from ,the mill tothe sepa` rator, means setting -up a carrying current of gas through the system, and means for introducing heat into the system ,whereby in pulverization sufficient moisture is evaporated and taken up by the gas, together with return piping from the separator to the mill, means for withdrawing Sufficient'io of the moisture laden gas from thesystem to prevent the moisture content from unduly rising, and means for supplyingV make;

In testimony whereof, "I have .hereunto signed my name. l

HENRY KRnIsINGER. 

